The smart cooling pump has been introduced in the cooling system of an internal combustion engine, which comprises at least one cylinder provided with an inner liner layer, an external engine block layer, and a coolant layer placed between the inner liner layer and the external engine block layer. The smart cooling pump guarantees good thermal conditions to the engine and avoids drag of the smart cooling pump if not required by the engine thermal status. This component is in fact able to reduce both CO2 consumptions and pollutant emissions. In any case, the complexity and the criticality of the smart cooling pump require a method that is able to evaluate if the pump is actually working properly or not, that is to say, if the pump is actually switched on or off when the control system requires it. In fact, if the smart cooling pump is correctly diagnosed it is possible to take the correct recovery action in order to save the internal engine from damage in case the smart cooling pump is malfunctioning. It is also possible to finely control the coolant circuit system in order to save consumption and pollutant emissions when the smart cooling pump works correctly.
Several solutions have been proposed for performing on/off diagnosis of a smart cooling pump of an internal combustion engine based on the thermal behaviour of the internal combustion engine. Unfortunately, nowadays there is no valid signal to be monitored that could realistically take into account the effect of the thermal inertia and of the requested load of an internal combustion engine, thus making the proposed on-off diagnosis methods unreliable.
In particular, proposed solutions to evaluate the thermal inertia and the requested load of an internal combustion engine adopt a plurality of temperature sensors placed on each layer of the engine. Such temperature sensors measure the local temperature of each layer of the engine in order to evaluate the thermal behaviour of the engine in any working condition. In practice, at least one temperature sensor is placed on each layer of the engine so that it is possible to try to evaluate temperatures and heat flux variation during the functioning of the engine, that is to say, in a continuous way. Unfortunately, such a methodology does not consider in a precise way the thermal dynamic behaviour of the engine since the temperatures on each layer are measured only locally and it is rather difficult to estimate the average temperature on each layer of the engine. This results in a very unprecise estimate of the thermal behaviour of the internal combustion engine and, as a consequence, of the on/off diagnosis of the smart cooling pump.
Therefore, it is at least one object herein to provide a method for performing on/off diagnosis of a smart cooling pump, taking into account the engine thermal inertia and the requested load of the internal combustion engine, which is simple and reliable in predicting if the smart cooling pump is working correctly or not. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.